Burden of proof is the legal burden on a party to convince the adjudicating court or tribunal, whether on a preponderance of evidence of evidence (in Civil cases) or beyond reasonable doubt (in Criminal cases), as to the truth of some propositions or fact which are in issue and vital to his case.
In this sense, burden of proof refers to the ultimate burden of establishing a case. If a party on whom this burden lies fails to discharge it, the consequence of such a failure is the certainty of failure of his case, either in whole or in part. Thus, this burden is generally not discharged until the court finds in favour of the party on whom the onus lies. Also this burden never shifts but remains on the same party throughout the trial, which party is determined at the beginning of the trial.
Secondly, burden of proof denotes the obligation upon a party to adduce sufficient evidence on a particular fact to enable the court find in his favour on that particular fact. The penalty for failure to discharge this burden is the possibility or risk but not the certainty of losing the whole case or part of it.
When a party on who lies the evidential burden has discharged the burden, the burden is then shifted to the other party. The basic principle for burden of proof is that he who asserts an allegation must prove it. See Section 131 of the Evidence Act and the celebrated case of Ojukwu V. Obasanjo (2003) FWLR (pt 182)1766. The burden is discharged by tendering sufficient evidence. Evidence sufficient to discharge such burden may be given by a single witness. See the case of Akalezi V. The State.
Burden of Proof in Criminal Cases
The burden of proving the guilty of any person accused of any criminal offence is always on the prosecution. See Section 131 and 132 of the Evidence Act. This is by virtue of the general principle that he who asserts must prove. Finally, see S. 135(2) EA and S. 36(5) of the Constitution. See also the case of People of Lagos State V. The State were the Supreme Court recapitulated the rule that the law places the burden of proof on the prosecution to prove the guilty of the accused beyond reasonable doubt.
Exceptions to the General Rule
There are a few exceptional cases were the accused bears the burden of proof in criminal cases.
- Burden of proving exemptions, exceptions or qualifications: See S. 36(5) of the Constitution which state that: nothing in the provision of the subsection shall invalidate any law by reason only that, the law imposes on any person a burden of proving a particular fact. See also Section 139(1) AND 141(1) OF EA.
- Burden of proving insanity and intoxication: See the case of Edoho V. State, the law is that in all criminal cases everyman is presumed to be sane and to possess a sufficient degree of reason to be responsible to his crimes until the contrary is proved.
- Burden of proving facts within the knowledge of the accused: By Section 140 EA, where any matter or facts is especially within the knowledge of the accused person the onus of proving Such matter of fact lies on him. See the case of Christopher Oti V. I.G.P
- Burden imposed by other Statues: see Section 417 of the Criminal Code and S. 60 of the Pharmacy Act. See also the case of the Queen V. Ohaka were the Supreme Court held that the onus was on an appellant charged under Section 60 of the Pharmacy Act to prove that he had a poisonous drug in his possession without any intent that it should be used for an illegal purpose.
- The burden of proving the defence of alibi: See the case of Shehu V. The State were the Supreme Court held that ‘it is the duty of the accused person relying on an alibi to give details of the alibi he has set up to enable the prosecution or the police to investigate it.
- Burden of proving special pleas in Bar: where in a criminal trial, the defence raises either a pleas of autrefois acquit or autrefois convict, the burden of establishing the pleas is on the accused person. Autre fois acquit means a plea in bar of arraignment against the defendant who has been acquitted of the offence while autre foise convict refers to a plea in bar of arraignment against the defendant who has been convicted of the offence.